FIG. 1 illustrates a conventional Pilates reformer 100 having a carriage 110 for accommodating a user's body that rides on rails 120. The movement of the carriage 110 is tensioned through a series of springs 130 that are variably attached to a spring support bar 140 that is fixed in position relative to the rails 120. If no springs 130 are attached to the support bar 140, then the carriage 110 will ride freely on the rails 120 in response to a force applied by a user, such as by a user pulling on hand grips 150 that are attached to the carriage 110 by cords 160 or the like. To increase the resistance to movement of the carriage relative to the rails 120, to thereby make it more challenging for a user to move the carriage 110, additional springs 130 are successively attached to the spring support bar 140 until the desired spring tension is achieved.
In this example, the amount of spring tension experienced by the carriage 110 is a function of the inherent spring characteristics (i.e. material, length, diameter, pitch, number of winds, frequency of compression), the length of an attached spring 130 as defined between the carriage 110 and the support bar 140, the motion of the spring 130 relative to the support bar 140, and the number of springs 130 attached to the support bar 140 at a particular time. If all springs 130 have the same inherent characteristics, then the attachment of five springs 130 to the support bar 140 will generate five times the amount of tension as if only one spring 130 was attached. If each of the springs 130 has a different identifiable inherent characteristic, then the tension can be adjusted by attaching different combinations of springs 130 to the support bar 140, where there are thirty-two possible tension combinations with five springs 130, sixty-four possible tension combinations with six springs, and so on. In addition to the tension characteristics of each spring 130, the support bar 140 position can be adjusted to modify the length of travel of the carriage 110 on the rails 120. Thus, there are large variations in tension that can be achieved by modifying a variety of variables including the position of the support bar 140 and the number of springs 130 attached between the carriage 110 and the support bar 140.
In the above example, the ability to fine tune the tension is limited and can be somewhat challenging, especially if multiple adjustments are necessary in an exercise session. In the case of Pilates spring loaded machines in particular, the sequence of selecting the required resistance is typically not intuitive and not user friendly, and in many occasions the user is required to remember a certain spring combination, or to do a calculation on the spot. Therefore the user may possibly connect the springs incorrectly to achieve a total final resistance which is not what is desired. This may also be true for other types of exercise machines as well.
In addition, adjusting the required resistance in conventional exercise machines is generally inconvenient, requiring that the user stop and change position. Another source of inconveniency is particularly apparent when a machine is being used in a demonstration to several student users, for example. This situation is very common in Pilates classes, where depending on the numbers of students and the class room space, the students frequently cannot witness what adjustments are made as the springs and the adjustment thereof are typically obscured by the frame of the machine.
In addition, manually adjusting the tension can be disruptive and is subject to user error. There is a need, therefore, for a way to more accurately define and control the tension characteristics in an exercise device like the reformer 100 described above.